About River Otter Conservation

Otterly Amazing

Extending from the smallest seasonal streams high in the Sierras to the sprawling Delta and Bay, the San Francisco Bay watershed includes more than sixty-five thousand square miles of forests and farmlands, rivers and lakes, cities and towns… over forty percent of California’s land mass. Throughout the region, wherever you find healthy waterways, you are likely to find river otters.

Over the last two centuries, river otters all but disappeared from the San Francisco Bay watershed. While the fur trade was a significant cause, habitat destruction also shrank otter populations as expanding cities and agriculture leveled forests, filled in wetlands and polluted waterways. It wasn’t until the environmental protections of the late 20th century that otter populations were given the opportunity to recover. Now abundant, river otters inhabit approximately 75% of their original range.

North American river otters (Lontra canadensis) are an important part of the watershed ecosystem. As top predators, they consume many other animals, from insects and crayfish to rodents and birds. As the health of a stream, river or the Bay changes, so does the amount of the otters’ prey. In turn, so does the number of otters. In order to sustain a healthy population of otters, we need to protect and restore their habitat.

But river otters are as important to their environment as their habitat is to them. Without river otters to regulate prey populations, an overabundance of smaller animals can deplete the other animals and plants in the food web, disrupting the balance and resilience of the whole system. Without river otters, the ecosystem can become unstable.

Otter populations and ecosystem health go hand-in-hand. This makes otters a good “indicator species,” allowing us to learn how well our restoration efforts are working by monitoring otter populations. As charismatic and cute animals, they also serve as great ambassadors for connecting people with the importance of protecting their local watersheds.